Sale 1:

Sold with a key for Steaming Pom-Pommed Provocateur (Suggestion at 11)

http://www.tf2outpost.com/trade/29615854 - B/O of 12

Seller: https://backpack.tf/profiles/76561198024373006#!/compare/1523318400/1523404800

Buyer: https://backpack.tf/profiles/76561198087374666#!/compare/1523232000/1523404800

X = 10

Sale 2:

Sold for 9 keys

Seller: https://backpack.tf/profiles/76561198087374666#!/compare/1523664000/1524096000

Buyer: https://backpack.tf/profiles/76561198204701269#!/compare/1523923200/1524096000

X = 9

The item is now untraceable, and looking at the last owner’s compare link, it would appear as if it sold for 11 keys:

https://backpack.tf/profiles/76561198204701269#!/compare/1524096000/1524268800

However, the B/O was much lower, which would go against this:

http://www.tf2outpost.com/trade/29624314 - B/O of ~9.5

Steaming Pom:

https://backpack.tf/suggestion/5b02b4a9cf6c75455526b312

Sellers:

11 keys:

https://i.imgur.com/YMT7kfq.png

https://backpack.tf/item/1829378068

Sales at:

9

10

Going with 9-10.